The trees are known as Indian marker trees or trail trees and were bent by Native Americans in their youth to mark trails or other landmarks, like a creek crossing.

Houser’s mission: to protect the historic trees and their stories. The group has identified four marker trees and is looking into reports of 32 more across Texas.

Groups like Houser’s are popping up across the country to protect and maintain the trees.

Mountain Stewards, a nonprofit based in Jasper, Georgia has compiled a database of 1,850 marker trees in 39 states, reported the AP.Comment: Rock art also served Indians as a natural sort of guidepost. For more on that subject, see The Hopi's "Newspaper Rock."